Cable networks originally carried programming from an head end to subscribers over a network of coaxial cable. Over time, these networks have changed. Some cable networks now include fiber optic links as part of the network. This variety of cable network is colloquially referred to as an “hybrid fiber/coax” network.
An hybrid fiber/coax network typically includes an head end that broadcasts programming over the network to subscribers in a downstream direction. The network includes two main portions. The first portion of the network is optical links that connect the head end with a number of geographically dispersed distribution nodes. These nodes are referred to as “optical distribution nodes” or “ODNs.” At the ODNs, signals from the head end that carry the programming are converted from optical signals to electrical signals. The second portion of the network is coaxial links that connect the ODNs with subscriber equipment. The electrical signals are transmitted to the subscriber equipment over the coaxial cable links.
In recent years, the cable industry has experimented with systems that allow for bi-directional communication between subscriber equipment and the head end. This would allow for services such as video-on-demand, telephony and Internet traffic to be offered over a cable network. The upstream communication is typically reserved for transmission in the 5 to 42 MHZ frequency range.
One problem with such as system is the quality of signals that are transmitted over this return path from the subscriber equipment to the head end. The signals are subject to problems such as distortion and noise. Further, it is difficult to measure the effect of these influences on the signals.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for an improved return path for a hybrid fiber/coax network.